I had a problem with a part that when I edit any feature, a feature would go red and not be able to work. I couldn't even draw a sketch and do a cut extrude. The VAR narrowed it down to my configuration settings file that was used from 2016 had problems in the registry. I used a clean 2017 settings file and problem went away.

Try resetting your SW configuration to stock and then reset all your settings manually. (back up the sweetings you have now before doing this.)